Electronic Design

IC Charges Battery, Runs System Simultaneously

The highly integrated AAT3670 is a 1.6-A dynamic battery charger and power-manager IC for portable systems powered by single-cell Lithium-ion/polymer batteries. With an on-board battery charger, current-limited load switches, and control circuitry, the device lets users simultaneously charge their battery and run their system from an ac adapter or USB port without hurting the battery charge-cycle life or adding external load switches. The AAT3670 delivers the highest possible charge current and, thus, the fastest possible charge time, according to Advanced Analogic Technologies. A voltage-sensing charge-reduction loop monitors the ac adapter input and USB input voltages. This loop also automatically prevents voltage sags by throttling back the charge current on the battery, depending on how much current the system load requires. By automatically adjusting charge current only to the extent necessary to maintain input source voltage integrity, this feature helps to simultaneously ensure continuous system operation and minimize battery charge time.

Under heavy load conditions, depending on PCB layout, the internal IC temperature may increase. Traditional thermal protection is a simple thermal shutdown. But since the AAT3670 supplies power to operate the system, such a shutdown is considered a fault condition and cannot be tolerated. So the AAT3670 contains a digital thermal loop that measures the internal die temperature and reduces charge current if the die temperature exceeds the threshold.

The AAT3670 comes in a lead-free, thermally enhanced, 24-pin, 4- by 4-mm QFN package. It sells for $1.73 each in 1000-piece quantities.

For more information, go to www.analogictech.com.

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